Slide-valve for steam-engines



UNITED STATES PATENT CFFICE.

FRANCIS CURTIS, OF NEWBURYPORT, MASSACHUSETTS.

SLIDE-VALVE FOR STEAM-ENGINES'.

Specification forming part ot Letters Patent No. 106,669, datedAAugnst 23, 1870.

To all whom it 'may concern.-

Beit known that I, FnANcIs Gun'rrs, of Newburyport, in the county ot' Essex and State ot' Massachusetts, have invented a new and Improved Method ot' Constructing and Operating Steam-Engine Valves, and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the accompanying drawing, making a part of this specification, in which- Figure l is a perspective view of part ot' the steam-chest of a steam-engine, A being the cylinder-face or valve-seat, B B, portions of the sides of a steam-chest; C, a steam slide or valve, `working over two steam-ports and one exhaust-port, in the manner of an ordinary three-ported valve; F, a supplementary valve, (also three-ported;) G, a rocking shaft or pin for moving the valve-F by means of the arm f/ acting within the notched back s of the valve. WFig. 2 is a plan of the stationary parts, showing the seat A, the sides B B, with their grooves 0,0, the main steam-ports H and I, passing through the cylinder-faceto opposite ends of the cylinder, (which ,cylinder is not shown,) the exhaust-port-J, .thejports h and z', and exhaust-port'y', coveredby the supplementary valve, and the three supplementary steam-passages, (in dotted `lines,) which,

passingwithin the substance of the cylindertace, connect theport 7L with the opening 7.", the port j with J, and the port t' with l. Fig. 5 is a view of the lower lside of the valve C; Fig. 4, a horizontal section of valve C; Fig. 5, a vertical and longitudinal section of valve C; Fig. 6, a transverse section of the' same, and Fig. 7 a perspective view of the supplementary valve Flying on its side.

This improvement relates to that class of engines that is without crank or connecting rod, andhasl no rotary motions, and is designed to secure a sure and prompt movement ofthe steam-valve, which movement shall be determined and timed by the in ain engine, yet commenced and completed independently, and also to allow the use ot' sliding valves with plane wearing-faces, capable of wearing down by use, and still being kept steam-tight by thc pressurefot' steam bearing them down upon their seats. For this purpose I use the valve C, sliding over the steam-ports II and I and the exhaust-port J to allow the ingress ot' steam to alternate ends of a steam-cylinder, so as to act on alternate sides of a piston, and also to allow the steam to escape from the cylinder, when its work is done, by means of the hollow m in the i'ace of valve C, connecting the ports H and I alternately with the exhaust-port J.

Within the valve C, I construct a -supplementary steam-cylinder, K, containing a piston, D, with its piston-rod E passing through both cylinder-heads, and resting its ends in the grooves o o in the sides ot' the steam-chest, the steam being admitted to cylinder K alternately through ports X X on one side of piston l), and ports Y Y on the other side of the same, the valve, with the cylinder included, being free to move endwise, while the piston, being held by the two ends of its rod abutting upon the sides ot' the chest, remains stationary.

To the ports X X steam is conducted by the groove n in the valve-face, which groove slides over the opening 7s, so that when the supplementary valve F is moved by the main en gine, through the means ofthe arm g of the rocking shaft G,.to the position represented in Fig. l,

the steam enters, by port It, dotted passage l1 7c,

groooveaz, `and ports X X, to supplementaryv cylinder. K, and, by its elastic force, propels this cylinder to the left, uncovering main Vsteam-port I, the steam within the supplementary cylinder K at the right side of piston "D being at the same time exhausted, by the `ports Y Y, groove a', dotted passage lz', valverecess f, exhaust-passage (dotted) j, to the main exhaust-port J.

When the main engine shall have sutticiently complet-ed its stroke, by the steam admitted through port I, the rocker G, being by any suitable mechanical attachment (from the main piston) caused to vibrate, will move the supplementary valve F to the left extreme of its path. Thus the entire route ot' steam is reversed, the main valve C makes a stroke to the right, the main engine acts in a direction opposite to the previous motion, and so on, alternately and regularly. Thus the motion otl C is determined and tim ed by the main en gine moving the rocking shaft G and valve F, while the main valve C is moved and held in place alternately, from first to last, by the independent engine contained Within itself; and yet the valves are both slides, with plane faces,-

free to Wear Without disarran gement resulting from such Wea-r, and the piston-rod E, as the parts Wear away, drops lower in the grooves o o, the whole making a simple, certain, durable, and accessible arrangement for the purpose sought. It is totally different from those in which avalve, being started in some way by the main engine, has its motion completed by the pressure of steam on a supplementary piston connected to or Within the valve. Any

such device I (lo not claim; but

That I- claimas 'my invention, and desire to secure by Letters Patent, is

l. The grooves n n', With openings X X, Y Y, h 7c, and t' l, in combination with valves C and F, as herein set forth.

2. The cylinder-valve C, with its stationary piston D and rod E, when arranged, relatively to the respective ports and the slide F, substantially as describe( FRANCIS CURTIS.

Witnesses:

J oi-IN N. PIKE,

lALvIN P. MARTIN. 

